1. Field of the Invention
The present invention relates to a communication system in which a plurality of communication devices are network-connected in a vehicle or the like.
2. Description of Related Art
As well known in the art, there are many cases where a vehicle network system is configured, in which a plurality of electronic control units (ECUs) mounted in a vehicle are network-connected to transmit and receive information (vehicle information) of the ECU. Then, one of communication systems which configure the vehicle network system is a controller area network (CAN).
On the other hand, in the CAN, the amount of data capable of being transmitted by one communication message is restricted to 64 bits. Accordingly, in the related art, a communication system capable of efficiently using communication data taking into consideration the restriction of the amount of data is suggested. For example, Japanese Patent Application Publication No. 2008-120173 (JP 2008-120173 A) describes a system which performs adjustment over a plurality of ECUs through communication by the CAN.
The system described in JP 2008-120173 A includes a plurality of ECUs (units) communicably connected to a CAN bus, and is able to adjust illumination luminance of backlights of a plurality of ECUs through CAN communication. That is, each unit includes a luminance setting table in which the same table data is set. Each luminance setting table has Table 1 to Table 10, and as the same table number, a numerical value correlated with another unit is set. Then, each ECU receives an instruction to change a table data number through CAN communication, thereby adjusting luminance of the backlight referring to the luminance setting table.
On the other hand, in recent years, with high function of the vehicle intended for improvement of convenience or the like, each ECU requires more information for processing for realizing high function. However, as described above, in a vehicle network, such as a CAN having the restriction of the amount of data, it is difficult to achieve an increase in the amount of data communicable between the respective ECUs, and it is not easy to change a vehicle network to a configuration capable of communicating a lot of data.